What are the factors of 405?

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Answer 1 · 2016-10-26T16:04:59

factors ${1, 3, 9, 15, 27, 45, 81, 135, 405,}$ ${1,3,9,15,27,45,81,135, 405, }$

A factor of a number is a number that divides exactly into that number eg. 4 is a factor of 16.

To find factors try and pair them up.

for 405

$1xx405=405 :. 1 & 405$ are factors

5 divides into 405 so:

$5xx81=405$

now since $81$ is a factor and NOT a prime number all the other factors of $81$ must be factors of $405$

we have 3, 9, 27
now find pairs.

$3xx135 =405$

$9xx45$

$27xx15$

now check other combinations of the factors

$3xx81=243$ not a factor; once we are half way there are no more factors.Similarly for all other combinations.

factors ${1,3,9,15,27,45,81,135, 405, }$